Currently most patients seeking general dental care in the US receive a complete-mouth set of x-rays as part of their initial dental examination. Recently the Center for Devices and Radiological Health (CDRH) issued a report advocating instead, the use of a limited set of x-rays for this initial examination. the intent of the guidelines is to reduce patient radiation exposure without compromising patient care by decreasing the number of unnecessary radiographs. To date, no studies have measured the efficacy of the guidelines. There is, however, evidence that the use of such guidelines results in missed disease. The aim of this study is to evaluate whether clinical application of these guidelines reduces the number of radiographs ordered (patient exposure) as well as whether their comparison group study design with the patient as his own control is used. Three dentists will use the guidelines to order periapical radiographs for approximately 700 new adult patients who do not already have a usable set of radiographs. A complete-mouth series will then be exposed. Data about the dental disease from patient periapical radiographs will be collected in a paired, blinded manner. One set of diagnosis data will come from the selected periapicals. A separate independent diagnosis will be made from the complete-mouth set. The disease information from the two sets will be compared. The major lines of analysis will include examining: the reduction in number of periapical radiographs ordered for adult patients at time of initial of clinical indications, and the extent of missed diagnostic findings from the selected radiographic examination and the degree of interpretation errors. Further, it is anticipated that modifications in the guidelines will be proposed that will increase their clinical utility. The results of this study will provide validation of the guidelines, which if suitable, may lead to their improvement and general adoption.